The present invention relates to a camera head-detachable image sensing apparatus, an image processing apparatus, and an image sensing system constituted therewith and, more particularly, to an image sensing apparatus and an image processing apparatus, connected to each other via a cable, and an image sensing system.
A variety of image sensing systems, so-called head-detachable cameras, using a solid-state image sensing device, such as a charge-coupled device (CCD), have been proposed. In such systems, an image sensing unit (camera head) and a signal processing unit for processing signals from the image sensing unit and outputting as video signals are separately configured, and connected with a cable.
Further, an image sensing apparatus using CCD has been down-sized and down-weighed, and a variety of methods for processing image signals, obtained from a CCD, in digital form by using high-speed analog-digital (A/D) and digital-analog (D/A) converters, realized in the progress of semiconductor manufacturing technique, have been proposed.
Furthermore, as personal computers have been popularized, application of head-detachable cameras to a desk-top television conference system using the personal computers has been proposed.
As shown in FIG. 7, an example of a desk-top television conference system mainly configured with a camera head 1001, stereo microphones 1025 and 1026, a cable 1002, a camera control unit (CCU) 1003 provided in an expansion board for performing signal processes and controlling compression and expansion of input image and audio data, a host computer 1060, a host computer unit 1061 including the CCU 1003 and the host computer 1060, a keyboard 1063, a mouse 1064, a speaker 1065, and a monitor 1062.
FIG. 8 is a block diagram illustrating an internal configuration of a conventional image sensing system. In FIG. 8, reference numeral 1013 denotes a CCD; 1014, a correlated double sampling (CDS) circuit for performing correlated double sampling processing on an output signal from the CCD 1013 (CCD signal); 1015, an automatic gain controller (AGC) for controlling amplification of the CCD signal; 1027, a timing signal generator (TG) for generating timing signals necessary operating the CCD 1013, the CDS circuit 1014, and so on; and 1020, a microprocessor (MPU) for controlling each unit of the camera head 1001. The camera head 1001 having the units as described above is connected to the CCU 1003 via the cable 1002.
Further, reference numeral 1044 denotes an analog-digital (A/D) converter; 1009, a digital signal processor (DSP); 1010, a digital-analog (D/A) converter; and 1048, a microprocessor (MPU) for controlling each unit of the CCU 1003.
With the aforesaid configuration, a CCD signal and a clock signal (CLK) which is synchronized with the CCD signal, as well as a communication signal RX used for a communication between the MPU 1020 are the MPU 1048 are transmitted from the camera head 1001 to the CCU 1003 via the cable 1002. Further, a horizontal synchronizing signal (HD) and a vertical synchronizing signal (VD) used for establishing synchronization between the CCD 1013 and the DSP 1009, as well as a communication signal TX used for a communication between the MPU 1020 and the MPU 1048 are transmitted from the CCU 1003 to the camera head 1001.
The TG 1027 establishes horizontal synchronization between the DSP 1009 and the CCD 1013 in accordance with the HD signal, and also establishes vertical synchronization between the DSP 1009 and the CCD 1013 in accordance with the VD signal.
Further, the MPU 1048 communicates with the MPU 1020 using the communication signals TX and RX, and controls the AGC 1015 to adjust the gain for a CCD signal, and also controls an iris diaphragm and a zoom lens (not shown) of the camera head 1001.
The CCD signal is converted into digital signals by the A/D converter 1044 in synchronization with the clock signal CLK, applied with digital processes, such as filtering, color separation, xcex3 correction, matrix operation and clipping, which are necessary for color image signals by the DSP 1009. Thereafter, the processed signal is digital-analog converted by the D/A converter 1010, and outputted as a signal conforming to NTSC format (video signals). Regarding sound, microphones and audio cables are necessary besides the configuration as described above.
In the aforesaid example, however, there is a problem in which many signals, such as CCD signals, and the HD signal, the VD signal and the clock signal for synchronization, and the communication signals TX and RX, have to be interchanged between the camera head 1001 and the signal processing unit 1003. As a result, signal lines for transmitting and receiving these signals are necessary, which requires many components for signal transmission and reception, and prevent cost and size of the image sensing system from being reduced.
Further, there is a problem in which, when the length of the cable 1002 is changed, because of signal delay, the HD signal and the clock signal CLK may become out of synchronization. Furthermore, when a single CCD, each of whose pixels contributes different color component from color components contributed by the neighboring pixels, outputs a color CCD signal, if timing for outputting the color CCD signal and timing for processing the color CCD signal by a digital signal processor are out of phase by one pixel period, a signal of inverted color is outputted. For example, a cyan-and-green signal is processed in the manner for processing a yellow-and-magenta signal, and vice versa.
The present invention has been made in consideration of the above situation, and has as its object to provide a camera head-detachable image sensing apparatus, an image processing apparatus, and an image sensing system constituted therewith, capable of reducing the number of signal lines between the camera head and the CCU.
According to the present invention, the foregoing first object is attained by providing an image sensing system which includes: (1) an image sensing apparatus comprising: image sensing means for sensing an object and outputting an image signal; first input means for inputting a reference clock signal from an image processing apparatus; first synchronizing signal generation means for generating a plurality of synchronizing signals on the basis of the reference clock signal input from the image processing apparatus and generating a composite synchronizing signal by multiplexing the generated synchronizing signals; first output means for outputting the composite synchronizing signal generated by the first synchronizing signal generation means to the image processing apparatus; time-divisional multiplexing means for multiplexing first control data on the image signal in a time-division manner on the basis of the synchronizing signals generated by the first synchronizing signal generation means; second output means for outputting the image signal and the first control data which are multiplexed in the time-division manner by the time-divisional multiplexing means to the image processing apparatus; and second input means for inputting second control data from the image processing apparatus; (2) the image processing apparatus comprising: third input means for inputting the composite synchronizing signal from the image sensing apparatus; second synchronizing signal means for separating the composite synchronizing signal inputted by the third input means into a plurality of synchronizing signals and outputting the synchronizing signals; third output means for outputting the second control data to the image sensing apparatus on the basis of the plurality of synchronizing signals generated by the second synchronizing signal generation means; clock signal generation means for generating the reference clock signal; fourth output means for outputting the clock signal generated by the clock signal generation means to the image sensing apparatus; and fourth input means for inputting the image signal on which the first control data is multiplexed from the image sensing apparatus; and (3) a cable for connecting between the image sensing apparatus and the image processing apparatus, wherein the cable connects the first input means, the second input means, the first output means and the second output means of the image sensing apparatus to the fourth output means, the third output means, the third input means and the fourth input means of the image processing apparatus, respectively.
It is another object of the present invention to provide a camera head-detachable image sensing apparatus, an image processing apparatus, and an image sensing system constituted therewith, capable of reducing the number of signal lines between the camera head and the CCU, in which synchronization between the camera head-detachable image sensing apparatus and the image processing apparatus is not dissolved and inversion of color signals do not occur even when the length of a cable connecting between them is changed, since the change in the length does not cause the signal delay.
According to the present invention, the foregoing object is attained by providing an image sensing system which includes: (1) an image sensing apparatus comprising: image sensing means for sensing an object and outputting an image signal; clock signal generation means for generating a reference clock signal; first output means for outputting the clock signal generated by the clock signal generation means to an image processing apparatus; first synchronizing signal generation means for generating a plurality of synchronizing signals on the basis of the reference clock signal generated by the clock signal generation means and generating a composite synchronizing signal by multiplexing the generated synchronizing signals; second output means for outputting the composite synchronizing signal generated by the first synchronizing signal generation means to the image processing apparatus; time-divisional multiplexing means for multiplexing first control data on the image signal in a time-division manner on the basis of the synchronizing signals generated by the first synchronizing signal generation means; third output means for outputting the image signal and the first control data which are multiplexed in the time-division manner by the time-divisional multiplexing means to the image processing apparatus; and first input means for inputting second control data from the image processing apparatus; (2) the image processing apparatus comprising: second input means for inputting the composite synchronizing signal from the image sensing apparatus; second synchronizing signal generation means for separating the composite synchronizing signal inputted by the second input means into a plurality of synchronizing signals and outputting the synchronizing signals; fourth output means for outputting the second control data to the image sensing apparatus on the basis of the plurality of synchronizing signals generated by the second synchronizing signal generation means; third input means for inputting the reference clock signal from the image sensing apparatus; and fourth input means for inputting the image signal on which the first control data is multiplexed from the image sensing apparatus; and (3) a cable for connecting between the image sensing apparatus and the image processing apparatus, wherein the cable connects the first input means, the first output means, the second output means and the third output means of the image sensing apparatus to the fourth output means, the third input means, the second input means and the fourth input means of the image processing apparatus, respectively.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.